def sayHello(name,week='',weather=''): #定义三个函数,分别是 name,week,weather
    print("Hello "+ name +".",end='') 
    print(("Wish you have a nice "+ week +".") if week !='' else '',end='')
    print(("We have a "+ weather + "day,isn't it?") if weather !='' else '')
sayHello('zhang') #Hello zhang.
sayHello('zhang','Friday','good ') #Hello zhang.Wish you have a nice Friday.We have a good day,isn't it?
sayHello(name = 'zhang',weather= 'fine ') #Hello zhang.We have a fine day,isn't it?
sayHello('zhang',week= 'Monday') #Hello zhang.Wish you have a nice Monday.


'''
显示效果如下:

Hello zhang.
Hello zhang.Wish you have a nice Friday.We have a good day,isn't it?
Hello zhang.We have a fine day,isn't it?
Hello zhang.Wish you have a nice Monday.

'''
